Sodium Benzoate

Sodium benzoate is the sodium salt of benzoic acid, widely used as a food preservative and antimicrobial agent (FDA GRAS). In automotive coolant formulations, it serves as a corrosion inhibitor, particularly protecting aluminum surfaces in modern engine cooling systems. Its broad-spectrum antimicrobial properties also help prevent microbiological contamination of coolant systems. At the concentrations used in consumer antifreeze products (1.5–5%), sodium benzoate does not carry a GHS hazard classification. The compound is readily biodegradable and has low aquatic toxicity (LC50 fish 484 mg/L at 96h, which is above the H400 threshold of 1 mg/L and H413 threshold of 10 mg/L for long-term classification, so no H4xx classification applies). The compound's inclusion in coolant poses no environmental classification concern at product-level concentrations.